Alarm system



United States Patent 3,340,521 ALARM SYSTEM Jesse L. Patterson, Jr.,William R. Quinn, and Earl R.

Quinn, Houston, Tex., assignors, by mesne assignments,

to Automatic Sprinkler Corporation of America, Houston, Tex., acorporation of Ohio Filed May 21, 1964, Ser. No. 369,232 5 Claims. (Cl.340258) This invention relates to alarm systems, particularly of thetype which may be installed in institutions or other large buildings forcausing an alarm responsive to the presence of an intruder.

Most intruderfalarm systems, for instance, those energized by theopening of a window or a door, are subject to malfunctioning or to beingtricked. Where the alarm is sound sensitive, it may be energized bysounds not caused by an intruder. Accordingly, there is need for areliable intruder alarm system which will be energized to give an alarm,with reasonable certainty, only when an intruder is present.

Accordingly, an object of the present invention is to provide a novelintruder alarm system with such safety features as to render the alarmsubstantially inoperable by occasional or expected sounds.

Another object is to provide a sound-sensitive alarm system includingmeans for preventing the operation of the alarm device whenexpectedsounds are produced in the monitored region, for instance, the strikingof a clock or the like. V 7

Another object is to provide a sound-sensitive alarm system which is notenergized by occasional random sounds.

In accordance with the present invention, there is provided an alarmsystem which incorporates any number of microphones located in thevicinity of regions to be protected and circuits connecting themicrophones through suitable amplifiers with an audible or other alarmdevice. One or more additional microphones are located. near expectedsounds and connected into the circuitry in such a way as to prevent thegiving of a signal responsive to such sounds. Furthermore, the circuitryincludes repeater means whereby a sound must be repeated. apredetermined number of times within a definite time interval, ascharacteristic of sounds produced by an intruder, in order to set otlfthe alarm.

Finally, the microphones or other circuitry may be desensitized tosounds of certain quality, for instance, road noises.

In the accompanying drawing which illustrates the invention the figureis a diagrammatic representation of exemplary circuitry used.

In the figure, there are shown four monitoring microphones 5, 6, 7, and8, although any number may be provided, which are located in the areasto be protected. All of these microphones are connected throughresistances 9, 10, 11, and 12 and acondenser 13 to amplification stage Aincluding a transistor 15 and thermionic tubes 16, 17, and 18,resistances and capaci tances being interposed in the amplifier circuitin conventional manner as shown. Electrical energy for the transistor issupplied through wires 19-23 inclusive. The anodes of tubes 16, 17, and18 are connected through wires 24, 25, 26, and 27 to positive DC. powerline 28, in turn connected through diode rectifier 29 to secondary 30 oftransformer 31. The anode of tube 18, also, is connected through acondenser 33 and a full-wave rectifier, including diodes 34 and 35 andthence to the grid of a tube 36. The cathodes of tubes 16 and 17 aregrounded.

The winding of a relay B is connected by a wire 39 to the cathode oftube 36 so as to function as a cathode :follower, responsive to anexcitation of one of the microphones 5, 6, 7, or 8. Relay B has anormally open contact B-l which is grounded and thereby serves to shuntthe relay winding through resistance 37 to eliminate or reduce thedifferential normally existent between the relay energizing andde-energizing voltages. Normally open relay contact B-2 is connected bya wire 40 through the winding of a relay C to a power source 41controlled by two pole switch 42. Relay pole contact B-2 connects via awire 43 to the other main power line 44. Relay C has a double throwcontact pole C-1 and a pair of contacts 45 and 46. Pole C1 connectsthrough a condenser 47 to ground. Relay contact 45 is connected by wires48 and 49 to a positive DC. power source, including transformersecondary 30, a diode rectifier 29, and a resistance 51. The other endof secondary 30 is connected to ground across the normally open contacts52 of a thermal switch D, the heater 53 of which is connected acrossA.C. power lines 41 and 44.

The other contact 46 of relay C is connected by a wire 56 and resistance57 to a condenser 58 and also through a wire 59 to a condenser 60 and awire 61 to a neon bulb 62. A high ohmage resistance 63 shunts condenser60 and bulb 62. Wires 59 and 61 and resistance 63 are grounded at 64.Wire 56 is also grounded through a shock absorber condenser 65 and isconnected by a wire 68 through a diode rectifier 69 to the normally opencontact 70 of a relay E. Previously mentioned condenser 58 is connectedby a wire 71 to the grid of a thermionic tube 72. The cathode of tube 72is grounded at 73, While the anode of this tube is connected by a wire74 through a condenser 75 to the grid of a tube 76. The winding of relayE is connected to the cathode of tube 76, as a cathode follower, whilethe anode of tube 76 is connected by a wire 77 to the positive D.C. line28.

The heater unit of a thermal switch F is connected, during operation bywires 80 and 81 across D.C. positive line 28 through contact of relay Eand wire 68 leading to contact 46 of relay C. The contact 83 of thermalswitch F connects ground through wires 84 and 85 to wire 86 connectingcondenser 75 to the grid of tube 76.

Relay E has two double-throw contact poles E1 and 13-2. Relay pole E-1is grounded at 87. Normally closed relay contact 88 is connected by awire 89 to the cathode of amplifier tube 18 so as to normally enable theamplifier. Normally open relay contact 70, previously mentioned, groundswire 68 leading through diode 69 and resistance 57 from previouslymentioned contact 46 of relay C. Normally closed relay contact 91,associated with relay contact pole E-2, which is connected to ground,closes a circuit through wire 92, which is connected to ground, and wire93 for energizing an all clear signal 94. Normally open contact 95, alsoassociated with relay pole contact E-2, serves through wires 92 and 96to energize an alarm, as an audible alarm 97, this being responsive, aswill be explained, to an intruder created signal.

The remainder of the circuit is for the purpose of preventing expectedsounds from energizing the alarm. At

100 is represented a microphone which would be positioned in thevicinity of an expected sound, as a striking clock, mechanicalrefrigerator, or the like. This microphone is connected by a wire 101and condenser 102 through three-stage amplification tubes 103, 104, and105 to a full-wave rectifier, including diodes 106 and 107 with shuntingcondenser 108 and resistance 109. The anodes of the tubes are connected,respectively, by wires 110115, inclusive, to positive D.C. line 28. Thecathodes of these tubes are provided with grounds and grid leakresistances, as shown. A wire 116 connects full-wave rectifier 106, 107to wire 117 connecting full-wave rectifier 34, 35 to the grid of tube36. The purpose of this circuitry, as will be explained, is to cancelout a signal impressed on cancellation microphone 100 and alsotransmitted through one of the alarm microphones 5, 6, 7, or 8. Wire 101is also connected by a wire 118 including resistance 119 to negativepotential source wire 19.

The apparatus operates as follows: When the system is monitoringnormally and under conditions when no alarm should be given, normallyclosed E relay contact 88 may be used to energize a signal, forinstance, a bulb 94, to indicate that everything is in order. Now, incase an energizing sound is picked up by one of the alarm microphones 5,6, 7, or 8, but not by cancellation microphone 100, the resultant energywill be amplified by means A, rectified by diodes 34 and 35, and appliedas a positive pulse to the grid of tube 36. Tube 36, then, will becomeconducting causing energization of the winding of cathode follower relayB, which through normally open relay contacts B-2 will energize thewinding of relay C. Relay pole C1,, normally, engages contact 45 whichdirects a charge from transformer secondary 30 and wires 49 and 48 uponcondenser 47. Upon the switching of relay pole C-1 into engagement withcontact 46, condenser 47 will be discharged into condensers 58 and 60.The capacity of condenser 47 is very much smaller than that ofcondensers 58 and 60 so that several pulses from condenser 47 arenecessary to fully charge condensers 58 and 60. Conveniently, condenser47 may be of .15 microfarads capacity and condensers 58 and 60 ofsufficient capacity that about five discharges from condenser 47 and,consequently, five signal pulses from the alarm microphones, arenecessary to fully charge condensers 58 and 60. Of course, condenser 47is recharged each time relay pole C-l returns to normally closed contact45. When the charge on capacitors S8 and 60 reaches approximately 70volts, neon lamp 62 fires, discharging condensers 58 and 60, generatinga negative pulse on the grid of tube 72. The accumulated charges oncondensers 58 and 60 may leak off through resistance 63, in an exemplaryembodiment of the value 22,000,000 ohms, so that the impulses fromcondenser 47 necessary to fully charge condensers 58 and 60 must occurwithin a predetermined time interval. The reason for this is that it ischaracteristic of an intruder that the noises caused will be repeatedand, thus, random and other noises not repeated sufficiently within thepredetermined time interval will not set 011 the alarm because, in theintervening time, condensers 58 and 60 may discharge through resistance63.

The discharge of condensers 58 and 60, as explained, has the effect ofrendering the grid of tube 72 more negative, and, therefore, the anodeof this tube becomes more positive, causing a positive pulse to besupplied through line 74, resistors 120, 121, and 122, and wire 86 tothe grid of tube 76. This then energizes the cathode following windingof relay E causing its pole contacts 13-1 and E-2 to reverse. Suchreversal of pole E1 connects relay contact 70 to ground to complete thedischarge of condensers 58 and 60. The reversal of relay pole E-2energizes contact 95 and wire 93 to produce a signal, as through theaudio device 97. Shifting of relay contact E-l, as stated, causes supplyof positive energy to the grid of tube 76, through wire 80, the heaterof thermal relay F, resistances 121 and 122 and wire 86, in efiect,latching relay E in alarm condition. However, contacts 83 of thisthermal relay will close after a predetermined interval, grounding thegrid of tube 76 and unlatching relay E to stop the alarm. The sameeffect may be achieved, to stop the alarm signal, by closing resetbutton 123 or by closing a key switch 124.

In case of a sound which is monitored by the cancellation microphone100, the amplified energy resultant therefrom is converted into anegative pulse by diodes 106 and 107 and fed through wire 116 whence itis added algebraically to the positive pulse generated in wire 117 bythe effect of the same sound on one of the alarm microphones. Thisprevents the energization of cathode follower relay B and the resultantshifting of counting relay pole C-1.

It should be further noted that while contacts E-1 are closed amplifier18 is disabled and hence the signals detected by microphones 5, 6, 7 and8 have no effect on the circuit operation.

A secondary winding 125 supplies energy through wire 19 to the filamentsof all of the tubes and also to microphones 58 through wires 21, 22, and23 and to transistor 15 through a wire 126. At 128 and 129 are shownfilter condensers for the power supply.

Various features of the circuitry may be modified as will occur to thoseskilled in the art. The wires 92 and 93 controlled by relay pole contactE-2 may be utilized for a purpose other than illuminating a ready lamp,or may serve no purpose in connection with the system. Moreover, thealarm may be tied in with a communication system throughout thebuilding. The invention may be modified in these and other respects aswill occur to those skilled in the art, and the exclusive use of allmodifications as come within the scope of the appended claims iscontemplated.

I claim:

1. In an alarm system, an electric circuit including in series amicrophone,

means for converting microphone excitations to electrical energy, and

the first contacts of a double throw switch;

a second circuit including a first condenser,

a source of condenser charging current for charging said condenserthrough said first switch contacts when said switch is in a firstposition;

a third circuit including a second condenser,

the other of contacts of said switch, and

an alarm device; means responsive to acoustical excitation of saidmicrophone for shifting said switch from said first to said secondposition for discharging said first condenser into said secondcondenser,

the capacity of said second condenser being sufficiently greater thanthat of said first condenser so that a predetermined number ofdischarges from said first condenser are required to charge said secondcondenser to a preselected voltage level; and

circiut means connected to said second condenser for responding to saidpreselected voltage level to discharge said second condenser and toinitiate energization of said alarm device.

2. An alarm system as described in claim 1 further including aresistance connecting said second condenser to ground in a manner tobleed oflf the charge on said second condenser to establish a timeinterval during which said shifts of said switch must occur in order toenergize said alarm device.

3. An alarm system as described in claim 1, further including anamplifier initially activated by the overcharge of said secondcondenser,

a relay for energizing said alarm device activated by the output fromsaid amplifier,

means for maintaining the activation of said amplifier after its initialactivation, and

a thermal switch for disabling said amplifier after a predeterminedperiod.

4. In an alarm system, a first electrical circuit including amicrophone,

an amplifier, and

6 the Winding of a relay having a double throw movable responding tosaid charge of preselected magnitude to contact and first and secondcontacts for alternative energize said alarm device and to substantiallydischarge engagement thereby, said winding being activated said secondcapacitance. by a signal from said amplifier; 5. The combinationdescribed in claim 4, further ina second circuit including 5 eluding aresistance for delaying bleed off of said second said movable contact,and capacitance for a predetermined period such that said prea firstcapacitance operably connected thereto; determined number of chargetransfers between said a third circuit including capacitance must occurwithin a predetermined time insaid first relay contact, and terval tocause energization of said alarm device. a source of condenser chargingcurrent for charging said capacitance when said movable contact is in aReferences Cited f t n i a; 1 d. UNITED STATES PATENTS a o circui mcu mgsaid second relay contact, g i 340-461 a second capacitance operablyconnected thereto, and 2329570 9/1943 W an alarm device connected foroperation in response 2428290 9/1947 P ekens 340 258 to 'a charge ofpreselected magnitude on said second 2435996 2 capacitance; and /1948Band 340-258 an operative connection between said microphone and g 1791'8 said relay movable contact through said amplifier agnalre' 3 10/1956Bagno 340258 and said wlndmg for shiftmg said movable contact 2 826 75311/1958 Ch 340 258 to a second position in engagement with said secondapm relay contact in response to acoustical excitation 7012 9/1959Pltman 340 '261 X 2 925 583 2/1960 Jeffers 34-0-37 of said microphone,thereby transferring the charge 2942247 6/1960 340 261 X on said firstcapacitance to said second capacitance, 3109165 10/1963 Blenau thecapacity of said second capacitance being sutfiagno 8 ciently greaterthan that of said first capacitance 5/1964 Kelly 340-261 3 155 954 11/1-964 Lar-rlck 340-261 so that a predetermined number of chargetransfers from said first capacitance to said second capaci- NEIL C.READ, Primary Examiner tance are required to charge said secondcapacitance to said preselected magnitude; and L TRAFTON, GOLDMAI;

circuit means connected to said second capacitance for Asslsllmf m s-

1. IN AN ALARM SYSTEM, AN ELECTRIC CIRCUIT INCLUDING IN SERIES AMICROPHONE, MEANS FOR CONVERTING MICROPHONE EXCITATIONS TO ELECTRICALENERGY, AND THE FIRST CONTACTS OF A DOUBLE THROW SWITCH; A SECONDCIRCUIT INCLUDING A FIRST CONDENSER, A SOURCE OF CONDENSER CHARGINGCURRENT FOR CHARGING SAID CONDENSER THROUGH SAID FIRST SWITCH CONTACTSWHEN SAID SWITCH IS IN A FIRST POSITION; A THIRD CIRCUIT INCLUDING ASECOND CONDENSER, THE OTHER OF CONTACTS OF SAID SWITCH, AND AN ALARMDEVICE; MEANS RESPONSIVE TO ACOUSTICAL EXCITATION OF SAID MICROPHONE FORSHIFTING SAID SWITCH FROM SAID FIRST TO SAID SECOND POSITION FORDISCHARGING SAID FIRST CONDENSER INTO SAID SECOND CONDENSER, THECAPACITY OF SAID SECOND CONDENSER BEING SUFFICIENTLY GREATER THAN THATOF SAID FIRST CONDENSER SO THAT A PREDETERMINED NUMBER OF DISCHARGESFROM SAID FIRST CONDENSER TO A PRESELECTED VOLTAGE LEVEL; AND ONDCONDENSER TO A PRESELECTED VOLTAGE LEVEL; AND CIRCUIT MEANS CONNECTED TOSAID SECOND CONDENSER FOR RESPONDING TO SAID PRESELECTED VOLTAGE LEVELTO DISCHARGE SAID SECOND CONDENSER AND TO INITIATE ENERGIZATION OF SAIDALARM DEVICE.